The document, addressed to Begum’s mother, said the decision was taken “in light of the circumstances of your daughter”.

“I would be very grateful if you could ensure the Home Secretary’s decision is brought to her attention, along with her right to appeal,” it added.

The east London schoolgirl who left Britain as a 15-year-old was tracked down to a refugee camp in northern Syria last weekend by The Times.

Subsequently she has been interviewed on Sky News and the BBC, with her comments being broadcasted and subject to intense debate around the world.

International law forbids nations from making people stateless by revoking their only citizenship, but it is possible Begum, who is of Bangladeshi heritage, held dual citizenship.

Government guidance from 2017 states that the Home Secretary has the power to order the deprivation if it would be “conducive to the public good”, as long as they are not left without any citizenship.

A Home Office spokesman said he could not discuss individual cases, but added: “We don’t leave people stateless.”

Begum and two of her school friends, Kadiza Sultana and Amira Abase, originally made the headlines when they fled Bethnal Green, London to travel to Syria to join IS in February 2015.

The teenager’s family have begged the government to intervene, saying that while they expect her to face consequences, she had been through a lot of trauma in the last four years, adding that her new born baby was “entirely blameless”.

The government, however, has so far been unclear in its response to the debate. Ben Wallace the security minister ruled out launching a rescue mission to Syria, saying he would not put British lives at risk to “go and look for terrorists or former terrorists”, adding that “actions have consequences”.

But culture secretary Jeremy Wright told the BBC’s Andrew Marr show that Begum should be allowed to return to the UK, saying that Britain was “obliged” to take back its citizens.

“I think it’s clear that if you’re dealing with a British citizen who wants to return to this country – and they’re not a dual citizen, so their only citizenship is British citizenship – then we are obliged at some stage at least to take them back.

“That doesn’t mean that we can’t put in place the necessary security measures to monitor their activities and make sure that they are not misbehaving.”

On Monday her family’s lawyer said he anticipated she would face criminal proceedings upon any return to the UK, but that it was the family’s hope she would be given professional help following her experience in Syria.

Metropolitan Police Commissioner Cressida Dick then confirmed the 19-year-old could expect to be “spoken to” and that counter-terrorism police officers are poised to “deal whatever they are confronted with” if she comes back to Britain.

One of the three, Sultana was reportedly killed in Raqqa when a suspected Russian air strike obliterated her house. The fate of Abase, and another schoolgirl who left Britain in 2014, is not known but they may still be alive.

Begum, who married an IS fighter soon after arrival, had two children who both died in recent months said to be because of illness and malnutrition. Her third child was born in the refugee camp over the weekend.

This is a breaking news story and will be updated. Follow HuffPost UK on Twitter here, and on Facebook here.